lim f(x,y) (x^4y^4)/(x^2 + y^4)^3

x,y go to (0,0)

this limit does not exist and to prove that you must take the limit using two different directions and I did one limit on the x-axis y=0 and the limit is 0. Now i must use the equation y=x^1/2 and i can't find the limit of this equation i keep on getting lim=1/2. can someone help me please?